11.5 Threads Per Inch Possible On Pm1236?

I'm new to the machining world so this might be a simple answer for some of you more experienced guys , but can a PM1236 be modified to cut finer than 60TPI?
 
Lynrob said:
I have a PM1236 lathe and I need to make a part with 11.5 threads per inch. 11.5 is not listed in the threading chart on the side of the lathe but I was wondering if there is a way to do it? Also, the change gears on my lathe are so tight that I need to use a gear puller to get them off. Is that normal?
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11.5 TPI is NTP standard for 1", 1.25", 1.5", and 2" pipe.
 
falconer said:
can a PM1236 be modified to cut finer than 60TPI?
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I don't know what you're after, but my lathe right is set up for chasing 400 TPI, (.0025 per rev feed) I'm not threading, just turning a diameter, but with a sharp enough threading tool, I could be chasing threads.
 
falconer said:
I'm new to the machining world so this might be a simple answer for some of you more experienced guys , but can a PM1236 be modified to cut finer than 60TPI?
Click to expand...

The answer is in what do you have for change gears? Most lathes are capable of far more feed rates (aka thread pitches) than they list. So if you set up for 60 tpi, do you have additional gears in your set that can create a finer feed? I don't have access to the specs to give a better answer so start with what you know and do the math by inserting other gears into the equation.
Dave
 
I don't know how similar your qc gearbox is to the one on my pm1440 but I ended up using the formula, standard driving gear x gearbox setting(in tpi) divided by standard driven gear x desired tpi and came up with 48 driver/46 driven, then set the lathe to cut 11 tpi. This setting and the above mentioned change gear combination produced the desired 11.5 tpi threads.

Hello, my name is Brian and I'm a toolaholic!
 
Thanks! I'll give that a try!


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